Field of the Invention
The present invention relates to wireless communication, and more particularly, to a method and apparatus for wireless communication in heterogeneous networks.
Related Art
A long term evolution (LTE), which has been made based on 3rd generation partnership project (3GPP) technical specification (TS) release 8, is a leading next-generation mobile communication standard.
As disclosed in 3GPP TS 36.211 V8.7.0 (2009-05) “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation (Release 8)”, the physical channels of the LTE may be divided into a physical downlink shared channel (PDSCH), which is downlink channel, and a physical uplink shared channel (PUSCH) and a physical uplink control channel, which are uplink channels.
The PUCCH is an uplink control channel which is used in transmitting uplink control information such as a hybrid automatic repeat request (HARQ), an ACK/NACK signal, a channel quality indicator (CQI), and a scheduling request (SR).
Furthermore, 3GPP LTE-A (advanced), which is an evolved version of the 3GPP LTE, is in progress. Some examples of the technologies, which are introduced in the 3GPP LTE-A, are carrier aggregation and a multiple input multiple output (MIMO) which supports 4 or more antenna ports.
The carrier aggregation uses a plurality of component carriers. The component carrier is defined as the central frequency and bandwidth. One downlink component carrier or a pair of an uplink component carrier and a downlink component correspond to one cell. A terminal, which is provided a service using a plurality of downlink component carriers, is provided services from a plurality of serving cells.
In the time division duplex (TDD) system, the downlink and the uplink use the same frequency. Hence, one or more downlink subframes are associated with the uplink subframe. The term “connected” implies that transmission/reception in the downlink subframe is connected to the transmission/reception in the uplink subframe. For example, if the transmission block is received in a plurality of downlink subframes, the terminal transmits HARQ ACK/NACK for the transmission block in the uplink subframe which is connected to the plurality of downlink subframes.